International Application No. PCT/AU99/00185 (referred to below as the International Application) disclosed several aspects of systems for fixing or releasing a first element and a second element. In one aspect, a fastener was adapted to releasably fix the first and second elements and included a locking means moveable by remote activation between a locked position and an unlocked position. There was no permanent material connection between the fastener and the remote activation means. A “material connection” was defined as a connection which had physical substance, i.e. substance made of matter, and excluded a connection made through energy.
Various examples of remote activation means were given. These included the use of magnetic attraction or repulsion, the use of high-frequency heating or radio frequency heating, the transmission of a message via radio or other waves, and so on.
It has now been found that certain “smart” materials may be adapted for fixing and release systems which have different features from the remotely activated systems referred to above and that such materials can have substantial advantages when applied as part of the invention described below.
Part of the motivation for the present invention in a first aspect was the desire to provide a fastener which is useful in assembly and also in disassembly. Disassembly is becoming increasingly more important with an increase in social pressure to recycle components, for example, those in mobile or cellular telephones. The invention is also based on the desire to provide a system of fasteners which can be part of an array, which can be individually addressable and which can enable an orderly, predictable way of accessing replaceable components in assemblies, for example, in order to remove a radio unit from a motor vehicle.
At least in some embodiments, the present invention finds a basis in the desire to utilise computer systems already established in many vehicles. One example of these is controller-area networking (CAN), in which modules communicate data on to a bus, usually requiring two wires; another example is the local interconnect network (LIN) bus, which uses a single wire and a single master/multiple slave configuration. The fasteners of the present invention may be useful in connection with these other “On Board Diagnostic Systems”.
The smart materials with which this invention is concerned (at least in the first aspect) are those known as “shape memory” materials. Currently, the best known of these is a shape memory alloy, predominantly or wholly made of titanium and nickel, but which may also include other material, such as aluminum, zinc and copper. Such a shape memory alloy is capable of adopting one shape below a predetermined transition temperature and changing to a second shape once its temperature exceeds the transition temperature. Conversely, when the shape memory alloy cools below the transition temperature, it is capable of adopting the first shape again.
While this invention encompasses use of the shape memory alloy referred to above, it is not limited to this material. It is contemplated that other suitable materials may exist now or may come into existence in the future which can be substituted for the shape memory alloy.
In a second aspect, this invention is concerned with a network of fasteners.
Monitoring of equipment status is becoming increasingly important. As one example, an aircraft monitoring system has been introduced recently under the name “Airplane Health Management”. The intention of such a monitoring system is to assist in streamlining aircraft maintenance and to minimise disruption to flight schedules.
A monitoring system such as the “Airplane Health Management” system desirably can carry out the functions of collecting data about the aircraft or other equipment being monitored and transmit the data to a central or remote processing system. For the aircraft example, the remote processing system may be on board the aircraft or it may be on the ground, so that problems, or potential problems, have already been identified before the aircraft lands. Maintenance can then be ready with the necessary labour schedule and/or parts to service the aircraft.
It is understood that aircraft maintenance is a significant cost, which at present is continuing to increase. It is also understood that a 10% reduction in maintenance costs may increase net profit by up to 40%.
It is an object of this invention to facilitate monitoring systems, especially monitoring systems in aircraft, but not limited to that application. It is a further object of this invention to enable not only monitoring but also a system which enables an action to be taken in response to the situation monitored.